Limitations of percutaneous insertion of Greenfield filters

Although it is technically possible to insert the standard stainless steel Greenfield filter (SGF) percutaneously using a 24 Fr. sheath, the incidence of insertion site venous thrombosis and the advantages of percutaneous technique have prompted the development of a titanium Greenfield filter (TGF) which can be inserted percutaneously through a 14 Fr. sheath or operatively. Clinical experience in 52 patients resulted in 51 placements (98%) with the majority below the renal veins (90%). One technical error resulted in caval penetration by the apex of the TGF without sequelae. One of the 19 deaths postinsertion was attributed to recurrent thromboembolism, and there was one additional event for a 4% recurrent embolism rate. At follow-up of 30 patients, averaging 5.2 months, all filters were patent and there were no proximal migrations. However, there was distal migration of 9-64 mm in 9 patients (30%) and tilting which increased from 8 patients at insertion to 12 at follow-up. Insertion site venous thrombosis occurred in 2 patients (7%) who were asymptomatic. Filter leg penetration of the vena cava was suspected in 9 patients (30%), but there were no clinical sequelae from this or the distal migrations. Since the clinical results of the TGF are comparable to the SGF, modifications of hook design should correct the tendency for wall penetration and distal migration.